Thermionic electron emitters are typically comprised of a refractory metal such as W coated with an oxide or diffusing oxide species that lowers the work function via electrostatic surface dipoles. The coating is necessary because although the refractory metals are stable and good conductors of electrons, they tend to have high work functions (on the order of 4.5 eV), and are therefore natively poor electron emitters unless a coating is included to lower their work function. Examples of thermionic emitters include impregnated W cathodes that have a low work function due to the formation of Ba—O dipoles[1] and scandate cathodes where a complex interplay between dipole formation and electron doping of Ba—O on Sc2O3 has been proposed to create a low work function.[1-3] These types of thermionic emitters have been employed in many high power electron beam applications[4, 5], and even thermionic energy conversion emitting layers rely on the same type of volatile surface dipole layers, such as Cs—O adsorbed on GaAs or InGaAs.[6, 7] However, these emission materials contain volatile surface species, which limits the lifetime and the efficiency of electronic devices which use thermionic electron emission processes.